Some Internet experts have long suggested that the rising tide of junk e-mail, or spam, would turn into a trickle if senders had to pay even as little as a penny for each message they sent. Such an amount might be minor for legitimate commerce and communications, but it could destroy businesses that send a million offers in hopes that 10 people will respond. The idea has been dismissed both as impractical and against the free spirit of the Internet.

Now, though, the idea of e-mail postage is getting a second look from the owners of the two largest e-mail systems in the world: Microsoft and Yahoo. Ten days ago, Bill Gates, Microsoft's chairman, told the World Economic Forum in Davos, Switzerland, that spam would not be a problem in two years, in part because of systems that would require people to pay money to send e-mail. Yahoo, meanwhile, is quietly evaluating an e-mail postage plan being developed by Goodmail, a Silicon Valley start-up company.

"The fundamental problem with spam is there is not enough friction in sending e-mail," said Brad Garlinghouse, Yahoo's manager for communications products. The company is intrigued by the idea of postage, Garlinghouse said, because it would force mailers to send only those offers a significant number of people might accept. "All of a sudden, spammers can't behave without regard for the Internet providers' or end users' interests," he said.